Audio gradually looses sync in long clips stitched by Fusion Studio

I've got a problem with audio sync in long clips. When I stitch long (30 minutes+) clips in Fusion Studio, the audio gradually gets out of sync with the video. The sync starts off perfect, but gradually gets worse, such that at the end of the clip, the audio is maybe 1/4 second ahead of the video. I thought this might be specific to how I'm playing the clips back, but that's not the case. It appears in any player I use, and also appears when I input the video to premier pro and export it from there. The only way I've found to fix this, is in premier pro, to unlock the video from the audio, and then use the 'rate stretch' tool to shorten the video very slightly until it is perfectly synced with the audio. (This results in the audio continuing a fraction of a second beyond the end of the video but that's no big deal). This happens regardless of how I render in fusion studio (5.2K, 4K even 2K) and stereo sound. I tried 360 sound, but that crashed Fusion Studio. Again, it only occurs (or is only noticeable) with very long clips towards the end of the clips. Strangly, the audio appears completely fine, when playing the video _inside_ Fusion Studio. The gradual loss-of-sync problem for long clips only occurs on the rendered output from Fusion Studio.

I'm using the latest Fusion firmware (1.8), the latest Fusion studio (1.3.0.400) and a Windows 10 laptop with 64GB and a Nvidia P5200 with 16GB.

Another piece of info: if I set start and end points at say 29 and 30 minutes in a 30 minute clip (i.e. just to stitch the last minute) then the audio is synced fine in the resulting 1 minute clip. The problem only seems to occur when the stitched output video is very long. It seems like the longer the stitch process proceeds, the more the audio and video get out of sync. Seems like the audio is getting rendered at a slightly different rate than the video.

I expect this may not be too noticeable for most folks, as rendering 30+ minute clips is not typical, and the sync issue is only apparent when playing towards the end of the clip. But I'd appreciate hearing from anyone on who have rendered 30+ minute clips in fusion studio, where the audio is perfectly synced with the video, right to the end of the clip.

That said, I'd highly appreciate itif someone would do this experiment and let me know the result. Would help me know if my unit is defective or not:

- Record a 30 minute clip. At the 29th minute, do something in the video that makes some sound (eg. talk).

- Import the video into fusion and render it as a 360 video (any settings).

- Then playback the video with Gopro VR player, and jump to the 29th minute to see if the audio is perfectly synced with the video.

Hello @foggystorm65787. This issue should have been fixed with the update. As there are particular settings involved as well as specific stitching process done, it would be best to get in touch with our Fusion team through Support. You may reach them by phone or chat through https://gopro.com/help/ContactUs . When you do, have camera and computer system information, and sample clips ready so they can take a closer look.

The update refers to the latest update, which your Fusion has now. Have you received an email from Support? There was one sent two days ago with instructions as part of troubleshooting. Please check your email and see if you got it. The Fusion team is waiting for an update in order to proceed to the next step. Thanks!

@mariustanya So you are saying the latest update has fixed a problem which fits the exact description I gave ? ie. gradual loss of audio sync on very long (20+ mins) videos rendered by fusion studio ?

Also, here is the last update I received from GoPro support :

"We were still on process of investigating your concern. As a test if there are problems on the versions of GoPro Studio, we would suggest to have temporarily try the previous version of Fusion Studio and see if it's doing the same."

To me, this is saying: we are still working on your problem,... but in the mean time, we'd SUGGEST that you try the previous version.

But you are saying GoPro support is waiting for something from me ? If that is the case, they should have been very clear in their response that they need something from me in order to proceed, rather than SUGGESTing.

Secondly, why would they ask me to try the previous version, if that is known to have an issue ?!

At any rate, I'm travelling right now, without access to the machine with all my videos. I'm pretty sure that the I did try the issue with the previous version and saw the same problem, but was going to wait till I get home to check to make sure, as I will not have access to the machine and fusion until I get home to try the previous version.

But, why can't the GoPro support team proceed to debug this issue on their own ? Have they tried to reproduce it ?